I need to replace two of the fire bricks in my Harman TL300. The dealer says harman specs a brick for earlier models that cost $45 each andone for later models for $15 each. Both are 6x12x1.5 inches, my stove is an early model which requires the expensive bricks (just my luck). Does anyone know that the difference is between the two bricks? Will it hurt my stove to use the cheaper bricks if they are indeed the same size? Does anone know of a place online to purchace harman parts which may be cheaper than my local dealer?